// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_DISK_CACHE_BLOCKFILE_EVICTION_H_
#define NET_DISK_CACHE_BLOCKFILE_EVICTION_H_

#include "base/macros.h"
#include "base/memory/weak_ptr.h"
#include "net/disk_cache/blockfile/rankings.h"

namespace disk_cache {

class BackendImpl;
class EntryImpl;
struct IndexHeader;

// This class implements the eviction algorithm for the cache and it is tightly
// integrated with BackendImpl.
class Eviction {
public:
    Eviction();
    ~Eviction();

    void Init(BackendImpl* backend);
    void Stop();

    // Deletes entries from the cache until the current size is below the limit.
    // If empty is true, the whole cache will be trimmed, regardless of being in
    // use.
    void TrimCache(bool empty);

    // Updates the ranking information for an entry.
    void UpdateRank(EntryImpl* entry, bool modified);

    // Notifications of interesting events for a given entry.
    void OnOpenEntry(EntryImpl* entry);
    void OnCreateEntry(EntryImpl* entry);
    void OnDoomEntry(EntryImpl* entry);
    void OnDestroyEntry(EntryImpl* entry);

    // Testing interface.
    void SetTestMode();
    void TrimDeletedList(bool empty);

private:
    void PostDelayedTrim();
    void DelayedTrim();
    bool ShouldTrim();
    bool ShouldTrimDeleted();
    void ReportTrimTimes(EntryImpl* entry);
    Rankings::List GetListForEntry(EntryImpl* entry);
    bool EvictEntry(CacheRankingsBlock* node, bool empty, Rankings::List list);

    // We'll just keep for a while a separate set of methods that implement the
    // new eviction algorithm. This code will replace the original methods when
    // finished.
    void TrimCacheV2(bool empty);
    void UpdateRankV2(EntryImpl* entry, bool modified);
    void OnOpenEntryV2(EntryImpl* entry);
    void OnCreateEntryV2(EntryImpl* entry);
    void OnDoomEntryV2(EntryImpl* entry);
    void OnDestroyEntryV2(EntryImpl* entry);
    Rankings::List GetListForEntryV2(EntryImpl* entry);
    void TrimDeleted(bool empty);
    bool RemoveDeletedNode(CacheRankingsBlock* node);

    bool NodeIsOldEnough(CacheRankingsBlock* node, int list);
    int SelectListByLength(Rankings::ScopedRankingsBlock* next);
    void ReportListStats();

    BackendImpl* backend_;
    Rankings* rankings_;
    IndexHeader* header_;
    int max_size_;
    int trim_delays_;
    int index_size_;
    bool new_eviction_;
    bool first_trim_;
    bool trimming_;
    bool delay_trim_;
    bool init_;
    bool test_mode_;
    base::WeakPtrFactory<Eviction> ptr_factory_;

    DISALLOW_COPY_AND_ASSIGN(Eviction);
};

} // namespace disk_cache

#endif // NET_DISK_CACHE_BLOCKFILE_EVICTION_H_
